export interface ImportEntry {
  project_name: string
  client_name?: string
  task_name?: string
  description?: string
  start_time: string
  end_time?: string
  duration: number
  tags?: string[]
}

export function parseCSV(text: string): string[][] {
  const lines = text.split('\n').filter(l => l.trim())
  return lines.map(line => {
    const cells: string[] = []
    let current = ''
    let inQuotes = false
    for (const char of line) {
      if (char === '"') {
        inQuotes = !inQuotes
      } else if (char === ',' && !inQuotes) {
        cells.push(current.trim())
        current = ''
      } else {
        current += char
      }
    }
    cells.push(current.trim())
    return cells
  })
}

export function parseDurationString(dur: string): number {
  // Handle HH:MM:SS, HH:MM, or decimal hours
  if (dur.includes(':')) {
    const parts = dur.split(':').map(Number)
    if (parts.length === 3) return parts[0] * 3600 + parts[1] * 60 + parts[2]
    if (parts.length === 2) return parts[0] * 3600 + parts[1] * 60
  }
  const hours = parseFloat(dur)
  if (!isNaN(hours)) return Math.round(hours * 3600)
  return 0
}

export function mapTogglCSV(rows: string[][]): ImportEntry[] {
  // Toggl CSV format: Description, Project, Client, Task, Tag, Start date, Start time, End date, End time, Duration
  const header = rows[0].map(h => h.toLowerCase())
  const descIdx = header.findIndex(h => h.includes('description'))
  const projIdx = header.findIndex(h => h.includes('project'))
  const clientIdx = header.findIndex(h => h.includes('client'))
  const taskIdx = header.findIndex(h => h.includes('task'))
  const tagIdx = header.findIndex(h => h.includes('tag'))
  const startDateIdx = header.findIndex(h => h.includes('start date'))
  const startTimeIdx = header.findIndex(h => h.includes('start time'))
  const durationIdx = header.findIndex(h => h.includes('duration'))

  return rows.slice(1).map(row => ({
    project_name: row[projIdx] || 'Imported',
    client_name: clientIdx >= 0 ? row[clientIdx] : undefined,
    task_name: taskIdx >= 0 ? row[taskIdx] : undefined,
    description: descIdx >= 0 ? row[descIdx] : undefined,
    start_time: combineDateTime(row[startDateIdx], row[startTimeIdx]),
    duration: durationIdx >= 0 ? parseDurationString(row[durationIdx]) : 0,
    tags: tagIdx >= 0 && row[tagIdx] ? row[tagIdx].split(',').map(t => t.trim()) : undefined,
  }))
}

export function mapGenericCSV(rows: string[][], mapping: Record<string, number>): ImportEntry[] {
  return rows.slice(1).map(row => ({
    project_name: row[mapping.project] || 'Imported',
    client_name: mapping.client >= 0 ? row[mapping.client] : undefined,
    task_name: mapping.task >= 0 ? row[mapping.task] : undefined,
    description: mapping.description >= 0 ? row[mapping.description] : undefined,
    start_time: row[mapping.start_time] || new Date().toISOString(),
    duration: mapping.duration >= 0 ? parseDurationString(row[mapping.duration]) : 0,
  }))
}

function combineDateTime(date: string, time: string): string {
  if (!date) return new Date().toISOString()
  if (!time) return new Date(date).toISOString()
  return new Date(`${date} ${time}`).toISOString()
}